Phong Nha, Ke Bang National Park - Phong Nha & Tien Son Caves: Caves are exquisite and very large. It is about 45 km by road from Dong Hoi and takes about an hour by motorbike. Thien Duong (Paradise) Cave is a cave in Phong Nha – Ke Bang National Park, UNESCO’s World Heritage Site, and 60 km northwest of Dong Hoi city. Thien Duong Cave is located on an elevation of 200 meters above sea level.